Many current semiconductor processes are performed at a temperature that is different than ambient temperature. For example, certain processes may be best performed in a cold environment, such as below 0° C., while others are best performed in a hot environment, such as above 500° C. Often, it is not the temperature of the ambient environment, but rather the actual temperature and/or the temperature uniformity of the workpiece that is of interest. Thus, monitoring the temperature of the workpiece itself may be beneficial.
Techniques for workpiece temperature measurement are limited by the processing environment. For example, thermocouples attached to the workpiece are impractical if the workpiece moves. Alternatively, thermocouples mounted to the supporting structure are of limited use, as the temperature of the supporting structure may differ from that of the workpiece due to problems associated with establishing good thermal contact between the supporting structure and the workpiece. Additionally, the optical properties of silicon make the application of common infrared techniques difficult or impossible. Additionally, in some embodiments, test workpieces are used to empirically measure the temperature of a workpiece, which is then assumed to be representative of all workpieces. However, in some embodiments, determination of an actual temperature of a workpiece being processed, and not a test workpiece, may be advantageous.
Thus, any system or method that allows for measurement of the temperature of a workpiece as that workpiece is being processed would be beneficial. Further, it would be advantageous if the measurement could occur while the workpiece is undergoing other processes, so as to maximize throughput.